/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hbase.util;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.RegionInfoBuilder;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility methods for interacting with the regions.
 */
@InterfaceAudience.Private
public abstract class ModifyRegionUtils {
    private static final Logger LOG = LoggerFactory.getLogger(ModifyRegionUtils.class);

    private ModifyRegionUtils() {
    }

    public interface RegionFillTask {
        void fillRegion(final HRegion region) throws IOException;
    }

    public interface RegionEditTask {
        void editRegion(final RegionInfo region) throws IOException;
    }

    public static RegionInfo[] createRegionInfos(TableDescriptor tableDescriptor, byte[][] splitKeys) {
        long regionId = System.currentTimeMillis();
        RegionInfo[] hRegionInfos = null;
        if(splitKeys == null || splitKeys.length == 0) {
            hRegionInfos = new RegionInfo[]{RegionInfoBuilder.newBuilder(tableDescriptor.getTableName()).setStartKey(null).setEndKey(null)
                    .setSplit(false).setRegionId(regionId).build()};
        } else {
            int numRegions = splitKeys.length + 1;
            hRegionInfos = new RegionInfo[numRegions];
            byte[] startKey = null;
            byte[] endKey = null;
            for(int i = 0; i < numRegions; i++) {
                endKey = (i == splitKeys.length) ? null : splitKeys[i];
                hRegionInfos[i] = RegionInfoBuilder.newBuilder(tableDescriptor.getTableName()).setStartKey(startKey).setEndKey(endKey).setSplit(false)
                        .setRegionId(regionId).build();
                startKey = endKey;
            }
        }
        return hRegionInfos;
    }

    /**
     * Create new set of regions on the specified file-system.
     * NOTE: that you should add the regions to hbase:meta after this operation.
     *
     * @param conf            {@link Configuration}
     * @param rootDir         Root directory for HBase instance
     * @param tableDescriptor description of the table
     * @param newRegions      {@link RegionInfo} that describes the regions to create
     * @param task            {@link RegionFillTask} custom code to populate region after creation
     * @throws IOException
     */
    public static List<RegionInfo> createRegions(final Configuration conf, final Path rootDir, final TableDescriptor tableDescriptor,
            final RegionInfo[] newRegions, final RegionFillTask task) throws IOException {
        if(newRegions == null)
            return null;
        int regionNumber = newRegions.length;
        ThreadPoolExecutor exec = getRegionOpenAndInitThreadPool(conf, "RegionOpenAndInitThread-" + tableDescriptor.getTableName(), regionNumber);
        try {

            /********
             * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
             *   注释：
             */
            return createRegions(exec, conf, rootDir, tableDescriptor, newRegions, task);
        } finally {
            exec.shutdownNow();
        }
    }

    /**
     * Create new set of regions on the specified file-system.
     * NOTE: that you should add the regions to hbase:meta after this operation.
     *
     * @param exec            Thread Pool Executor
     * @param conf            {@link Configuration}
     * @param rootDir         Root directory for HBase instance
     * @param tableDescriptor description of the table
     * @param newRegions      {@link RegionInfo} that describes the regions to create
     * @param task            {@link RegionFillTask} custom code to populate region after creation
     * @throws IOException
     */
    public static List<RegionInfo> createRegions(final ThreadPoolExecutor exec, final Configuration conf, final Path rootDir,
            final TableDescriptor tableDescriptor, final RegionInfo[] newRegions, final RegionFillTask task) throws IOException {
        if(newRegions == null)
            return null;
        int regionNumber = newRegions.length;
        CompletionService<RegionInfo> completionService = new ExecutorCompletionService<>(exec);
        List<RegionInfo> regionInfos = new ArrayList<>();
        for(final RegionInfo newRegion : newRegions) {
            completionService.submit(new Callable<RegionInfo>() {
                @Override
                public RegionInfo call() throws IOException {

                    /********
                     * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
                     *   注释：
                     */
                    return createRegion(conf, rootDir, tableDescriptor, newRegion, task);
                }
            });
        }
        try {
            // wait for all regions to finish creation
            for(int i = 0; i < regionNumber; i++) {
                regionInfos.add(completionService.take().get());
            }
        } catch(InterruptedException e) {
            LOG.error("Caught " + e + " during region creation");
            throw new InterruptedIOException(e.getMessage());
        } catch(ExecutionException e) {
            throw new IOException(e);
        }
        return regionInfos;
    }

    /**
     * Create new set of regions on the specified file-system.
     *
     * @param conf            {@link Configuration}
     * @param rootDir         Root directory for HBase instance
     * @param tableDescriptor description of the table
     * @param newRegion       {@link RegionInfo} that describes the region to create
     * @param task            {@link RegionFillTask} custom code to populate region after creation
     * @throws IOException
     */
    public static RegionInfo createRegion(final Configuration conf, final Path rootDir, final TableDescriptor tableDescriptor,
            final RegionInfo newRegion, final RegionFillTask task) throws IOException {
        // 1. Create HRegion
        // The WAL subsystem will use the default rootDir rather than the passed in rootDir
        // unless I pass along via the conf.
        Configuration confForWAL = new Configuration(conf);
        confForWAL.set(HConstants.HBASE_DIR, rootDir.toString());

        /********
         * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
         *   注释：
         */
        HRegion region = HRegion.createHRegion(newRegion, rootDir, conf, tableDescriptor, null, false);
        try {
            // 2. Custom user code to interact with the created region
            if(task != null) {
                task.fillRegion(region);
            }
        } finally {
            // 3. Close the new region to flush to disk. Close log file too.
            region.close();
        }
        return region.getRegionInfo();
    }

    /**
     * Execute the task on the specified set of regions.
     *
     * @param exec    Thread Pool Executor
     * @param regions {@link RegionInfo} that describes the regions to edit
     * @param task    {@link RegionFillTask} custom code to edit the region
     * @throws IOException
     */
    public static void editRegions(final ThreadPoolExecutor exec, final Collection<RegionInfo> regions,
            final RegionEditTask task) throws IOException {
        final ExecutorCompletionService<Void> completionService = new ExecutorCompletionService<>(exec);
        for(final RegionInfo hri : regions) {
            completionService.submit(new Callable<Void>() {
                @Override
                public Void call() throws IOException {
                    task.editRegion(hri);
                    return null;
                }
            });
        }

        try {
            for(RegionInfo hri : regions) {
                completionService.take().get();
            }
        } catch(InterruptedException e) {
            throw new InterruptedIOException(e.getMessage());
        } catch(ExecutionException e) {
            IOException ex = new IOException();
            ex.initCause(e.getCause());
            throw ex;
        }
    }

    /*
     * used by createRegions() to get the thread pool executor based on the
     * "hbase.hregion.open.and.init.threads.max" property.
     */
    static ThreadPoolExecutor getRegionOpenAndInitThreadPool(final Configuration conf, final String threadNamePrefix, int regionNumber) {
        int maxThreads = Math.min(regionNumber, conf.getInt("hbase.hregion.open.and.init.threads.max", 16));
        ThreadPoolExecutor regionOpenAndInitThreadPool = Threads
                .getBoundedCachedThreadPool(maxThreads, 30L, TimeUnit.SECONDS, Threads.newDaemonThreadFactory(threadNamePrefix));
        return regionOpenAndInitThreadPool;
    }
}
